def cross(p0, p1, p2):
    return (p1[0] - p0[0])*(p2[1] - p0[1]) - (p2[0] - p0[0])*(p1[1] - p0[1])

p0 = (2,3) 
p1 = (0,2) 
p2 = (0,0) 
print(cross(p0, p1, p2))
